Electromagnetically driven shutter and valve



Nov. 24, 1964 H. w. FULBRIGHT ELECTROMAGNETICALLY DRIVEN SHUTTER AND VALVE Filed May 31 United States Patent 3,158,350 ELECTROMAGNETICALLY DRIVEN SHUTTER AND VALVE Harry W. Fulbright, Rochester, N.Y., assignor to General Dynamics Corporation, New York, N.Y., a corporation of Delaware Filed May 31, 1961, Ser. No. 113,728 Claims. (Cl. 251137) This invention relates generally to a device for controlling the passage of a medium between predetermined points in a given path, and more particularly to an electromagnetically operated device for selectively controlling such passage.

Normally, a device for controlling the passage of a medium such as light, sub-atomic particles, or fluids between predetermined points in a given path, or from one area to another, includes a panel or wall separating a source of the medium from the area into which it is to be passed, and an aperture or the like formed in the wall to provide an opening through which the medium may pass. Means are provided in the control device for selectively closing and opening the aperture so as to control the passage of the medium therethrough.

In certain applications, the control devices which are presently available are not entirely satisfactory and/or cannot be employed. In this connection, in applications such as high speed photography, the control devices are not capable of opening and/or closing the aperture with the speed required.

In another of the applications, it is necessary to accurately time the admission of gas, or particles into a cham her with respect to the operation of other apparatus. For example, in the study of plasma a predetermined quantity of ionizable gas may be passed into a discharge tube immediately prior to the initiation of a discharge in the tube. Because of the manner of actuation of previously available control devices it is diflicult to accurately time their operation.

Accordingly, an object of this invention is the provision of a new and improved means for controlling the passage of a medium between predetermined points in a given path. An additional object of the invention is the provision of a control device for selectively permitting passage of a medium into and/or out of a predetermined area in an extremely short time interval. A further object is to provide a device for controlling such passage, which device can be selectively actuated with extreme accuracy. A still further object is to provide means for rapidly moving an obstructing material across the path of a medium and automatically braking the movement of the material.

Other objects and advantages of the invention will become known by reference to the following description and the accompanying drawing of one embodiment of the invention.

In the drawing:

FIGURE 1 is a partially broken-away perspective view of one embodiment of a control device in accordance with the present invention showing a medium-obstructing material in a non-obstructing position;

FIGURE 2 is a sectional view taken generally along line 22 of FIGURE 1,

FIGURE 3 is a fragmentary sectional view taken along line 33 of FIGURE 2; and

FIGURE 4 is an embodiment of a circuit diagram which may be used with the device of FIGURE 1 to provide automatic braking of the movement of that portion of the device which selectively obstructs the passage of the medium.

Generally, in accordance with the present invention, a device is provided for accurately controlling the passage Hce of a medium, such as light, sub-atomic particles, or fluid, between predetermined points in a given path. The control device includes a means for obstructing the passage of the medium, which means is selectively movable between a position in which the path of the medium is obstructed (hereinafter referred to as the obstructing position) and a position in which the path of the medium is unobstructed (hereinafter referred to as the non-obstructing position). The obstructing means is made of currentconducting material, and is moved to the obstructing position or to the non-obstructing position by the interaction of a current, which is selectively passed through the obstructing means, and a magnetic field which intersects the obstructing means.

For purposes of explanation, a control device is described hereinafter for selectively controlling the passage of light.

Referring now to the drawing, the electromagneticallyoperated device includes a housing 11 formed of a pair of co-extensive, parallel wall members 13 and 15 held in relative position by suitable connecting means (not shown) and separated from one another by a pair of spacing strips 17 disposed between the wall members, with one of the strips positioned adjacent each of the side edges of the housing. The wall members are therefore spaced slightly from one another so as to define a slot 19 between their opposing surfaces. Each of the wall members 13 and 15 is formed of material which can withstand the use to which the control device is subjected, such as glass epoxy.

In the illustrated embodiment, the wall members 13 and 15 are provided with narrow rectangular apertures 21 and 23, respectively, which serve as openings through which a beam of light may pass. Of course, if the housing were formed of a transparent material, the device would operate without the provision of apertures in the housing wall members. The apertures 21 and 23 are preferably in alignment with one another.

A means 25, capable of blocking the passage of light through the apertures 21 and 23, is slidably disposed in the slot 19 between the wall members 13 and 15. In the illustrated embodiment, the means is a thin elongated strip of current-conducting material such as aluminum foil. The ends of the strip project outwardly from the upper and lower ends of the housing and are connected to a suitable circuit such as that shown in FIGURE 4, to be described in detail shortly.

The strip 25 is provided with a narrow rectangular aperture 29 which, as illustrated, is smaller than the apertures 21 and 23 in the wall members 13 and 15. The aperture 29 is located in the strip 25 in such a position that when the strip is centrally positioned Within the slot 19, the aperture 29 is in alignment with the apertures 21 and 23 and, hence, the strip 25 is in its non-obstructing position. When the aperture 29 is on either side of the apertures 21 and 23, the strip is in an obstructing position. Therefore, by moving the strip 25 edgewise through the slot 19, the strip is moved from an obstructing position to a non-obstructing position and then to an obstructing position, thus effecting an opening and closing of the apertures 21 and 23.

The strip is supported in its movement within the slot 19 by the opposed surfaces of the wall members 13 and 15. The wall members are preferably pressed against the strip by a force exerted by the connecting means, previously referred to but not shown, which maintains the wall members in their relative positions.

In order that the strip 25 may be moved easily within the slot 19 without being affected by the elastic properties of the material, it is twisted by approximately as shown in FIGURE 1 at its upper and lower ends. In this way, the strip 25 flexes at the bends.

In the illustrated embodiment, means are provided for establishing a magnetic field substantially at a right angle to the plane of the strip 25. The means includes a pair of field coils 33 wound so as to define an air core of a diameter greater than the length of the apertures 21 and 23. The coils 33 are suitably supported so that the path of light through the apertures extends along the axes of the coils. Thus, the arrangement of the coils is such that when a current is passed through them, a concentrated magnetic field is established at the strip. The coils, as shown, are formed of relatively heavy wire, but the particular coils used can of course be varied with the application of the device.

In a preferred mode of operation of the device, a pulse of current is caused to flow in the coils 33, thereby establishing a magnetic field at the strip 25. At the same time, a high intensity current is caused to fiow in the strip 25. The [interaction of this current with the magnetic field produced by the coils 33 causes a force to be exerted on the strip, moving it past the apertures at a relatively high velocity and thereby effecting rapid opening and closing of the apertures.

It is preferable to provide a means for braking the movement of the strip 25 so that it does not become damaged upon contact with that portion of the walls of the housing which defines the limits of the slot 19. In the illustrated embodiment, the movement of the strip is braked electromagnetically by reversing the direction of current fiow through the strip immediately after the strip passes through its non-obstructing position. This is accomplished by making the current in the strip approximately equal to the time derivative of the high current pulse which is passed through the field coils. In this connection, the strip 25 is connected in series with the secondary coil 35 of a transformer and the current through the field coils is passed through a primary coil 39 of the transformer.

More specifically, and with reference to FIGURE 4, the field coils 33 and the primary coil 39 are connected in series with an energy storage means 41 such as a capacitor bank. A switch means 43, shown as an ignitron, but which might also be a Thyratron, etc., is connected in series with the capacitor bank and the field coils 33. The igniter of the ignition is connected through a switch 42 and DC. source 44 to the cathode thereof to provide a means for igniting the tube. The capacitor bank is charged by a high voltage, direct-current source 45 which is connected in parallel with the capacitor bank. A switch means 47 which permits selective charging of the capacitor bank and a current-limiting resistor 49 are connected in series with the source 45.

A resistor 51 is connected in series with the capacitor bank 41, which resistor dampens oscillations of the current in the field coils. A resistor 53 is connected in series with the strip 25 and the secondary coil 35, which resistor is of such a value as to make current in the strip approximately equal to the time derivative of the field coil current.

In operation of the braking means, the switch 47 is closed thereby charging the capacitor bank 41. At a predetermined time, the switch means 43 is closed, discharging the capacitor bank 41 through the primary coil 39, and hence, through the field coils 33, thus establishing a magnetic field which intersects the strip 25. The current through the primary coil 39 induces a voltage in the secondary coil 35 which causes a current to flow through the strip 25. The current in the strip is approximately equal to the time derivative of the current in the primary coil 39. Thus, the rise of the current pulse in the field coils induces a high current in the strip thereby causing the strip to move edgewise within the slot 19 and therefore across the apertures 21 and 23. This causes the aperture 29 of the strip 25 to move first into and then out of alignment with the apertures 21 and 23 of the wall members 13 and 15, and thus opens and closes these apertures and permits light to pass through the apertures for a short interval of time.

When the pulse of current reaches its maximum and starts to decrease, the current in the strip reverses and interacts with the remaining field of the field coils 33 to cause a force to be exerted on the strip 25 which is oppositely directed to the force caused by the rise of the pulse of current, thus braking the movement of the strip within the slot 19.

While one embodiment of the braking means has been described other means are possible. For example, a circuit might be used which would provide short, simultaneous drive pulses of current respectively through the coils 33 and the strip 25, followed at a predetermined time by equally strong braking pulses, but with the direction of one of the currents, for example, the strip current, reversed.

In the embodiment of the device described, the strip 25 is caused to move in one direction across the path of the medium, and may be returned manually to its initial or starting position. However, it should be clear that the strip could also be returned to its initial position by reversing the terminals of the secondary coil 35 and again discharging the capacitor bank 41.

In a specific embodiment of the control device, the movable strip is made of aluminum foil having a thickness of approximately 2 mils. The apertures in the strip and each of the housing walls are approximately 0.5 millimeter in width.

The field coils are of 3 turns, and are of the air-core type having a core diameter of 2 inches and are spaced 2 inches apart. The field coils have an inductance of approximately 0.4 micro-henries. The capacitance of the capacitor bank is micro-farads and the capacitor bank is charged to approximately 8000 volts.

The transformer is of the air-core type and the mutual inductance of the transformer is 0.4 micro-henries. The resistor in series with the secondary coil of the transformer has a value of approximately 0.06 ohm. The effective inductance of the circuit containing the capacitor bank is 4.7 micro-henries, and the resistance of that circuit is 0.47 ohm.

When the capacitor bank is discharged, a maximum current of about 12,800 amperes flows through the primary circuit. This current establishes a field at the strip of approximately 13,580 gauss. The interaction of the strip current and the field of the coils causes the strip to move approximately 1.5 millimeters at a maximum speed of about 5 l0 centimeters/second.

In certain applications it is sometimes desirable to use the device to control the passage of a fluid. In such applications, it may be expedient to include means for providing a seal around the apertures 21 and 23 between the wall members 13 and 15 and the strip. This may be accomplished by milling grooves around the apertures and either disposing O-rings in these grooves, or connecting a vacuum to the milled grooves (difierential pump system). The latter mentioned system would provide a shorter open time than the O-ring seals.

The embodiment of the housing 11 and-obstructing means 25 described above is useful in controlling the passage of light and any medium which is obstructed by the material of which the strip is made. For other mediums, the strip is formed of a material which obstructs the passage of that medium, for example, an aluminum strip might be used when the medium consisted of alpha particles. When the housing is formed of a material which is non-obstructing to the medium, such as a transparent material when the medium is light, and the path of the medium has a relatively small cross-sectional area, the apertures 21 and 23 in the housing wall members 13 and 15 would not be necessary.

A device has thus been described which makes it possible to control the passage of a medium between predetermined points on a given path with extreme accuracy.

The device represents an improvement over devices previously known in the art both in the brief length of time during which the aperture remains open, and in the accuracy with which the device can be actuated.

Although shown and described with respect to a particular embodiment, it will be apparent that various modifications might be made without departing from the principles of this invention.

What is claimed is:

1. A device for selectively controlling the passage of a medium into or out of a predetermined area, said device comprising means defining an aperture, means formed at least partially of a medium-obstructing material supported adjacent said aperture and adapted for selective movement to and between an obstructing and non-obstructing position relative to said aperture so as to selectively control the passage of a medium therethrough, said medium-obstructing means being formed at least partially of a current-conducting material, coil means disposed adjacent said medium-obstructing means for establishing a high intensity magnetic field which intersects the conducting portion of said medium-obstructing means, and means for applying a high amperage pulse of direct current through said field-producing coil means and for inducing a pulse of current in said conducting portion of said medium-obstructing means, the interaction of said induced current with the field produced by the passage of the applied current through said coil means being effective to cause movement of said obstructing means relative to said aperture so as to control passage of a medium therethrough.

2. An electromagnetically-driven device for selectively controlling the passage of a medium into or out of a predetermined area along a given path, said device comprising means defining an aperture pos1tioned along said path, means supported adjacent said aperture and adapted for selective movement to and between an obstructing and non-obstructing position relative to said aperture so as to selectively control the passage of a medium therethrough, said medium-obstructing means being formed at least partially of a current-conducting materlal and being provided with an opening disposed so as to become aligned with said aperture during a predetermined movement relative to said aperture, coil means for establishing a high intensity magnetic field which intersects the con-' ducting portion of said obstructing means, and means for selectively applying a high amperage pulse of direct current through said coil means and for inducing a single pulse of current in the conducting portion of said medium obstructing means, the current passing through the obstructing means being proportional to the time derivative of the current passing through the coil means, whereby the interaction of the current through said obstructing means and said magnetic field causes movement of said obstructing means in a given direction relative to said aperture so as to control passage of a medium therethrough.

3. An electromagnetically-driven device for selectively controlling the passage of a medium into or out of a predetermined area along a given path, said device comprising a wall defining an aperture positioned on said path, means supported adjacent said aperture and adapted for selective movement to and between an obstructing and non-obstructing position relative to said aperture so as to selectively control the passage of a medium therethrough, said medium-obstructing means being formed at least partially of a current conducting material and being provided with an opening disposed so as to become aligned with said aperture during a predetermined movement relative to said aperture, means for maintaining said medium-obstructing means in sliding relationship with said wall adjacent said aperture, coil means for establishing a magnetic field which intersects the conductive portion of said medium-obstructing means, and means for selectively causing a high amperage pulse of current to -flow through the conducting portion of said mediumobstructing means and through said coil means the current passing through the conducting portion of the medium-obstructing means being proportional to the time derivative of the current passing through the coil means, whereby the interaction of the current through said medium-obstructing means and said magnetic field causes movement of said obstructing means relative to said aperture so as to control passage of a medium therethrough.

4. An electromagnetically-driven device for selectively controlling the passage of a medium into or out of a predetermined area along a given path, said device comprising a housing having a pair of spaced-apart substantially parallel walls defining a slot therebetween, each of said walls having an aperture formed therein in alignment with each other on an axis substantially normal to the planes of said walls and generally colinear with the path of the medium, a current-conducting member formed at least partially of a medium-obstructing material disposed within said slot and adapted for selective movement to and between an obstructing and non-obstructing position relative to said aperture so as to selectively control the passage of a medium therethrough, coil means for establishing a high intensity magnetic field which intersects the conducting portion of said mediumobstructing means, and means for selectively applying a high amperage pulse of direct current through said coil means and for inducing a pulse of current in said medium-obstructing means, the current passing through the medium-obstructing means being proportional to the time-derivative of the current passing through the coil means, whereby the interaction of the current through said movable medium-obstructing means and said magnetic field causes movement of said obstructing means relative to said aperture so as to control passage of a medium therethrough.

5. An electromagnetiCally-driven device for selectively controlling the passage of a medium into or out of a predetermined area along a given path, said device comprising a housing having a pair of spaced-apart substantially parallel walls defining a slot therebetween, each of said walls having an aperture formed therein alignment with each other on an axis substantially normal to the planes of said walls and generally co-linear with the path of said medium, a current-conducting member formed at least partially of a medium-obstructing material disposed with in said slot and adapted for selective movement to and between an obstructing and non-obstructing position relative to the common axis of said apertures so as to selectively control the passage of a medium therethrough, said medium-obstructing member being provided with an opening disposed so as to become aligned with said apertures during a predetermined movement of said member relative to the common axis of said apertures, means connected to said housing to prevent said medium from assuming a path other than through said apertures, coil means for establishing a high intensity magnetic field which intersects the medium-obstructing member, and means for selectively applying a high amperage pulse of direct current through the medium-obstructing member and through said coils, the current passing through the medium-obstructing member being proportional to the time-derivative of the current passing through the inductive means, whereby the interaction of the current through said obstructing member and said magnetic field causes movement of said obstructing member relative to said apertures, so as to control passage of a medium therethrough.

6. An electromagnetically-driven device for selective ly controlling the passage of a medium into or out of a predetermined area along a given path, said device comprising means defining an aperture positioned along said path, means formed of a material adapted to obstruct the passage of said medium supported adjacent said aperture and adapted for selective movement transversely of said path, said movable medium-obstructing means being formed at least partially of a current-conducting: material and being provided with a non-obstructing area disposed so as to become aligned with said aperture during a predetermined movement relative to said aperture, coil means disposed adjacent said medium-obstructing means for establishing a high intensity magnetic field which intersects the conducting portion of said medium-obstructing means, and means causing a high amperage pulse of current to flow through said coil means and through the con ducting portion of said medium-obstructing means, whereby the interaction of the current through said mediumobstructing means and said magnetic field causes movement of said medium-obstructing means transversely of the path of said medium so as to bring said non-obstructing area into and then out of alignment with said aperture and thereby permit instantaneous passage of said medium along said path.

7. An electromagnetically-driven device for selectively controlling the passage of a medium into or out of a predetermined area along a given path, said device comprising means defining an aperture positioned along said path, means formed of a material adapted to obstruct the passage of said medium supported adjacent said aperture and adapted for selective movement transversely of said path, said medium-obstructing means being formed at least partially of a current-conducting material and being provided with an opening disposed so as to become aligned with said aperture during a predetermined movement relative to said aperture, coil means disposed adjacent said medium-obstructing means for establishing a magnetic field which intersects the conducting portion of said medium-obstructing means, and means for applying a high amperage pulse of direct current through said field-producing coil means and for inducing a single pulse of current in said conducting portion of said mediumobstructing means, whereby the interaction of the induced current through said medium-obstructing means and said magnetic field causes unidirectional movement of said obstructing means transversely of the path of said medium so as to bring said opening into and out-of alignment with said aperture and thereby permit instantaneous passage of said medium along said path.

8. An electromagnetically-driven device for selectively controlling the passage of a medium into or out of a predetermined area along a given path, said device comprising means defining an aperture positioned along said path, means formed at least partially of a mediumobstructing material supported adjacent said aperture and adapted for selective movement to and between an obstructing and non-obstructing position relative to said aperture so as to selectively control the passage of a medium therethrough, said medium-obstructing means being formed at least partially of a current-conducting material, means for establishing a magnetic field which intersects the conductive portion of said apertureobstructing means, and means for selectively applying a pulse of current through said coil means and for inducing a pulse of current in the conducting portion of said obstructing means comprising an energy-storing means electrically connected to said field-producing means, means electrically connected to said storing means for supplying energy thereto, means for selectively discharging said energy-storing means, and transformer means, the primary of which is electrically connected in series with said energy-storing means and said field-producing means and the secondary of which is electrically connected in series with the conducting portion of said medium-obstructing means, whereby the discharge of said energy-storing means energizes said field-producing means and causes a current to flow in said primary so as to induce a flow of current in said secondary and through said medium-obstructing means, interaction of said induced current with said field being effective to cause movement of said obstructing means in a given direction, collapsing of the flux of said primary being effective to induce a flow of current in the opposite direction in said secondary and through said obstructing means, interaction of said oppositely-directed current with the collapsing field of said field-producing means being effective to impart a braking force to said obstructing means and arrest movement thereof.

9. A device for selectively controlling the passage of a medium into or out of a predetermined area, said device comprising means defining an aperture, means formed at least partially of a medium-obstructing material supported adjacent said aperture and adapted for selective movement to and between an obstructing and non-obstructing position relative to said aperture so as to selectively control the passage of a medium therethrough, said medium-obstructing means being formed at least partially of a current-conducting material, coil means disposed adjacent said medium-obstructing means for establishaing a high intensity magnetic field which intersects the conducting portion of said mediumobstructing means, said coil means comprising at least two air-core coaxial coils disposed on opposite sides of said medium-obstructing means with their axes extending generally along the path of saidmedium, and means for applying a high amperage pulse of direct current through said field-producing coil means and for inducing a pulse of current in said conducting portion of said mediumobstructing means, the interaction of said induced current with the field produced by the passage of the applied current through said coil means being effective to cause movement of said obstructing means relative to said aperture so as to control passage of a medium therethrough.

10. A device for selectively controlling the passage of a medium between predetermined points in a given path, said device comprising means formed at least partially of a mediumobstructing material disposed intermediate said points and adapted for selective movement to and between an obstructing and a non-obstructing position relative to said aperture so as to selectively control the passage of a medium therethrough, said mediumobstructing means being formed at least partially of a current-conducting material, coil means disposed adjacent said medium-obstructing means for establishing a high intensity magnetic field which intersects the conducting portion of said obstructing means, and means for causing a high amperage pulse of current to fiow through said coil means and through said conducting portion of said medium-obstructing means, the interaction of said current in said conducting portion of said mediumobstructing means with the field produced by the passage of current through said coil means being effective to cause movement of said medium-obstructing means in a given direction relative to the path of said medium so as to control the passage of the medium along the path, and electrical means for braking the movement of said obstructing means in said given direction.

References Cited in the file of this patent UNITED STATES PATENTS 2,131,293 Miller July 5, 1935 

1. A DEVICE FOR SELECTIVELY CONTROLLING THE PASSAGE OF A MEDIUM INTO OR OUT OF A PREDETERMINED AREA, SAID DEVICE COMPRISING MEANS DEFINING AN APERTURE, MEANS FORMED AT LEAST PARTIALLY OF A MEDIUM-OBSTRUCTING MATERIAL SUPPORTED ADJACENT SAID APERTURE AND ADAPTED FOR SELECTIVE MOVEMENT TO AND BETWEEN AN OBSTRUCTING AND NON-OBSTRUCTING POSITION RELATIVE TO SAID APERTURE SO AS TO SELECTIVELY CONTROL THE PASSAGE OF A MEDIUM THERETHROUGH, SAID MEDIUM-OBSTRUCTING MEANS BEING FORMED AT LEAST PARTIALLY OF A CURRENT-CONDUCTING MATERIAL, COIL MEANS DISPOSED ADJACENT SAID MEDIUM-OBSTRUCTING MEANS FOR ESTABLISHING A HIGH INTENSITY MAGNETIC FIELD WHICH INTERSECTS THE CONDUCTING PORTION OF SAID MEDIUM-OBSTRUCTING MEANS, AND MEANS FOR APPLYING A HIGH AMPERAGE PULSE OF DIRECT CURRENT THROUGH SAID FIELD-PRODUCING COIL MEANS AND FOR 